The goal of this project is the identification of heritable characteristics of ion transport which may distinguish individuals with a primary affective disorder from normal controls. A study of sodium potassium stimulated adenosine triphosphatase (Na+ -K+-ATPase), a cation transport enzyme has been completed. Nak ATPase is a "state" but not a "trait" marker for affective illness. ATPase activity is decreased by arecoline, but this response does not differentiate patients from controls. We have engaged in a collaborative program of research on the lithium erythrocyte/plasma ratio in euthymic patients. We have confirmed an extended effect of lithium treatment on the ratio. Several other laboratories have asserted that lithium ratio is a genetic marker for a significant portion of bipolar patients. However, they have neglected this effect and may therefore be studying an artifact.